Ionic liquid based mixtures for gas storage and delivery

ABSTRACT

A mixture and method for the storage and delivery of a gas are disclosed herein. In one aspect, there is provided a mixture comprising: an ionic liquid comprising an anion and a cation, at least a portion of the gas that is disposed within and reversibly chemically reacted with the ionic liquid, and optionally an unreacted gas. In another aspect, there is provided a method for delivering a gas from a mixture comprising an ionic liquid and one or more gases comprising: reacting at least a portion of the gas with the ionic liquid to provide the mixture comprising a chemically reacted gas and an ionic liquid and separating the chemically reacted gas from the mixture wherein the chemically reacted gas after the separating step has substantially the same chemical identity as the chemically reacted gas prior to the reacting step.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/948,277, filed 23 Sep. 2004, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Many processes in the semiconductor industry require a reliable sourceof process gases for a wide variety of applications. Often these gasesare stored in cylinders or vessels and then delivered to the processunder controlled conditions from the cylinder. The semiconductormanufacturing industry, for example, uses a number of hazardousspecialty gases such as phosphine (PH₃), arsine (AsH₃), and borontrifluoride (BF₃) for doping, etching, and thin-film deposition. Thesegases pose significant safety and environmental challenges due to theirhigh toxicity and pyrophoricity (spontaneous flammability in air). Inaddition to the toxicity factor, many of these gases are compressed andliquefied for storage in cylinders under high pressure. Storage of toxicgases under high pressure in metal cylinders is often unacceptablebecause of the possibility of developing a leak or catastrophic ruptureof the cylinder.

In order to mitigate some of these safety issues associated with highpressure cylinders, on-site electrochemical generation of such gases hasbeen used. Because of difficulties in the on-site synthesis of thegases, a more recent technique of low pressure storage and deliverysystems has been to adsorb these gases onto a solid support. Thesestorage and delivery systems are not without their problems. They sufferfrom poor capacity and delivery limitations, poor thermal conductivity,and so forth.

BRIEF SUMMARY OF THE INVENTION

A mixture for the storage and delivery of a gas and a method and systemfor making and using same are disclosed herein. In one aspect, there isprovided a mixture for the storage and delivery of a gas comprising: anionic liquid comprising an anion and a cation; and a gas disposed withinthe ionic liquid comprising one selected from the group consisting of aboron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a halocarbonyl-containing gas, and anoxygen-containing gas wherein at least a portion of the gas isreversibly chemically reacted with the ionic liquid. In certainembodiments, the mixture further comprises an unreacted gas or a gasthat is not chemically reacted with the ionic liquid. In theseembodiments, the unreacted gas may be selected from an inert gas, anadditive gas, the unreacted portion of the chemically reactive gas, andmixtures thereof.

In another aspect, there is provided a method for the storage anddelivery of a gas comprising: providing an ionic liquid comprising ananion and a cation; contacting the gas with the ionic liquid underconditions sufficient to provide a mixture wherein at least a portion ofthe gas is chemically reacted with the ionic liquid; and separating atleast a portion of the gas from the ionic liquid. The chemical identityof the gas after the separating step is substantially the same as thegas prior to the contacting step. The gas disposed within the ionicliquid may comprise one selected from the group consisting of aboron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a carbonyl-containing gas, an oxygen-containinggas, and mixtures thereof.

In a further aspect, there is provided a mixture for storage anddelivery of a gas comprising: an ionic liquid having Lewis basicity andcomprising an anion selected from BF₄ ⁻, p-CH₃—C₆H₄SO₃ ⁻, CF₃SO₃ ⁻,(CF₃SO₂)₂N⁻, (NC)₂N⁻, (CF₃SO₂)₃C⁻, CH₃COO⁻ and CF₃COO⁻ and a cationselected from tetraalkylphosphonium, teraalkylammonium,N-alkylpyridinium, and 1,3-dialkylimidazolium; the gas wherein at leasta portion of the gas is reversibly chemically reacted with the ionicliquid to provide a chemically reacted gas wherein the chemicallyreacted gas has Lewis acidity and is selected from diborane, borontrifluoride, boron trichloride, phosphorous trifluoride, phosphoroustetrafluoride, silicon tetrafluoride, germane, germanium tetrafluoride,hydrogen cyanide, isotopically-enriched analogs, and mixtures thereof;and optionally an unreacted gas.

In a still further aspect, there is provided method for the storage anddelivery of a gas selected from the group consisting of aboron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a halocarbonyl-containing gas, anoxygen-containing gas and mixtures thereof comprising the steps of:providing an ionic liquid comprising an anion and a cation; reacting atleast a portion of the gas with the ionic liquid to provide a mixturecomprising an ionic liquid and a chemically reacted gas; introducing anunreacted gas comprising an inert gas into the mixture; and separatingat least a portion of the chemically reacted gas and optionally theunreacted gas from the mixture where the gas after the separating stephas substantially the same chemical identity as the chemically reactedgas prior to the reacting step.

In yet another aspect, there is provided a method method for the removalof at least a portion of an unreacted gas from a mixture comprising achemically reacted gas, an ionic liquid, and the unreacted gascomprising: providing the ionic liquid comprising an anion and a cationwithin a storage vessel; introducing the unreacted gas to the storagevessel comprising the ionic liquid wherein at least a portion of theunreacted gas resides within a headspace of the storage vessel; reactingat least a portion of a gas selected from the group consisting of aboron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a halocarbonyl-containing gas, anoxygen-containing gas and mixtures thereof with the ionic liquid toprovide the mixture comprising the ionic liquid, a chemically reactedgas disposed within the ionic liquid, and the unreacted gas; reducingthe temperature of the mixture to solidify the ionic liquid and providea solidified mixture comprising the ionic liquid and chemically reactedgas wherein the reducing decreases the solubility of the unreacted gasthereby causing the unreacted gas to evolve into the headspace; removingsubstantially all of the unreacted gas from the headspace; andincreasing the temperature of solidified mixture to provide a mixturesubstantially free of unreacted gas.

FIG. 1 is a graph of capacity of phosphine (PH₃) for a number ofdifferent reactive liquids, ionic liquids and a solid adsorbent.

FIG. 2 is a graph of capacity of boron trifluoride (BF₃) for variousmixtures described herein.

DETAILED DESCRIPTION OF THE INVENTION

Relatively few examples of mixtures that result from a chemical reactionbetween an ionic liquid and another compound such as one or more gasesexist to date. In most instances, ionic liquids act as solvents and donot undergo a chemical reaction with the at least a portion of the gascontained therein. The mixture described herein comprises an ionicliquid and one or more gases wherein the ionic liquid is chemicallyreacted with at least a portion of the gas disposed therein. Thechemical reaction between the ionic liquid and at least a portion of thegas is reversible; in other words, the chemical identity of at least theportion of the gas within the mixture that is reacted with the ionicliquid, upon separation from the ionic liquid, is substantially the sameas it was prior to addition to the mixture. The gas or gases may then beseparated from the mixture when needed. It is believed that thesemixtures broaden the use of ionic liquids for a variety of applicationsincluding, but not limited to, extraction, separation, and otherapplications. In one particular embodiment, the mixture may be used forthe storage and delivery of one or more gases to a point of use. Forexample, the mixture may contain a gas that is used, for example, as areagent for an ion implant process or in a vapor deposition process suchas atomic layer deposition or chemical vapor deposition.

In certain embodiments, the mixture may optionally comprise an unreactedgas The term “unreacted gas” as used herein describes one or more gasesthat are not chemically reacted with the ionic liquid. The unreacted gasmay be disposed within the ionic liquid as a result of intermolecularforces such as, without limitation, van der Waals forces or hydrogenbonding, disposed within the headspace of the vessel, or both. Theunreacted gas may comprise an additive gas or gases, an inert gas orgases, the unreacted portion of the chemically reacted gas, and mixturesthereof. In certain instances, the unreacted gas may be considered anadditive gas as defined herein whereas in other circumstances, theunreacted gas may be considered an inert gas as defined herein. Certaingases which are identified herein as an additive gas may be alsoidentified herein as an inert gas depending upon, but withoutlimitation, temperature, pressure, the identity of the chemicallyreacted gas, the identity of the ionic liquid, and other factors. Inembodiments wherein the unreacted gas comprises an additive gas, theterm “additive gas” describes a gas or gases that exhibit a differentchemical reactivity with the ionic liquid than the chemically reactedgas. For example, the additive gas could be chemically reacted with theionic liquid if the conditions (e.g., temperature, pressure, etc.)changed. In these embodiments, the additive gas could become achemically reacted gas upon a change in conditions such as the removalof at least a portion of the chemically reacted gas from the mixture.Particular examples of additive gases include, but are not limited to,carbon monoxide, carbon dioxide, oxygen, nitrogen, and mixtures thereof.In other embodiments wherein the unreacted gas comprises an inert gas,the term “inert gas” describes a gas or gases that are non-reactive tothe ionic liquid and/or the portion of the gas that is chemicallyreacted with the ionic liquid. Examples of inert gases include, but arenot limited to, nitrogen, helium, hydrogen, argon, xenon, krypton,radon, and mixtures thereof. One particular example of this embodimentis a mixture comprising an ionic liquid, PH₃ and nitrogen wherein atleast a portion of the PH₃ is chemically reacted with the ionic liquidand nitrogen is an unreacted inert gas. In still further embodiments,the mixture can comprise the unreacted portion of the gas that ischemically reacted with the ionic liquid. In these embodiments, only aportion of the gas chemically reacts with the ionic liquid to form themixture described herein thereby leaving an unreacted portion at aparticular pressure, temperature, and/or other condition. One particularexample of this embodiment is a mixture comprising an ionic liquid, PH₃that is reacted with the ionic liquid, and PH₃ that is dissolved withinbut is not reacted with the ionic liquid.

The term “chemical reaction” as used herein describes a chemicalinteraction involving intramolecular valence forces (e.g., covalent,dative covalent, coordinate, or electrovalent) between the ionic liquidand at least a portion of the gas disposed therein. In certainembodiments, the chemical reaction between the ionic liquid and at leasta portion of the gas may occur with at least one mole or greater of gasto one mole of ionic liquid. In alternative embodiments, the molar ratioof reacted gas to ionic liquid is substantially 1:1. It is believed thatat least one of the following phenomena has occurred to indicate thatthe chemical reaction to provide the mixture described herein hasoccurred: the phenomena can be characterized by chemical specificity;changes in the electronic state may be detected by one or moreanalytical methods (e.g., ultraviolet, infrared, microwave, or nuclearmagnetic resonance (NMR) spectroscopy; electrical conductive, ormagnetic susceptibility); the reaction may incur or release a certainamount of energy; and/or the elementary step upon reaction involves anactivation energy. Examples of chemical reactions that may occur betweenthe ionic liquid and the gas include, but are not limited to, Lewisacid/Lewis base reactions (e.g., coordination and Brøonsted acid/basereactions), metallic substitution reactions, and metallic oxidativeaddition reactions. The following are non-limiting examples of variouschemical reactions that provide the mixtures described herein.

Lewis Acid/Base Reactions:

-   BMIM⁺CuCl₂ ⁻+PH₃→BMIM⁺CuCl₂ ⁻:PH₃-   BMIM⁺Cu₂Cl₃ ⁻+2PH₃→BMIM⁺Cu₂Cl₃ ⁻:2PH₃-   BMIM⁺BF₄ ⁻+BF₃→BMIM⁺BF₄ ⁻:BF₃-   BMIM⁺[OSO₂OCH₂CH₂OCH₂CH₂OCH₃]⁻+4BF₃→BMIM⁺[F₃BOSO₃CH₂CH₂OCH₂CH₂OCH₃]⁻:3BF₃-   BMIM⁺CH₃SO₃O⁻+2BF₃→BMIM⁺[CH₃SO₃OBF₃]⁻:BF₃-   [A]⁻[MIM]⁺—G—CN+BF₃→[A]⁻[MIM]⁺—G—CN:BF₃-   [RMIM]⁺[A]⁻—G—OCH₃+MX_(n)→[RMIM]⁺[A]⁻—G—O(MX_(n))CH₃-   [RMIM]⁺[ML_(n)]⁻+L′→[RMIM]⁺[ML_(n)(L′)]⁻    Brøonsted Acid/Base Reactions:-   [A]⁻[MIM]⁺—G—NH₂+HX→[A]⁻[MIM]⁺—G—NH₃ ⁺X⁻-   [A]⁻[MIM]⁺—G—SO₃H+Z→[A⁻][MIM]⁻—G—SO₃ ⁻ZH⁺-   [RMIM]⁺[A]⁻—G—NH₂+HX→[RMIM]⁺[A]⁻—G—NH₃ ⁺X⁻    Metallic Substitution Reactions:-   [RMIM]⁺[MX_(n)]⁻+X′Y→[RMIM]⁺[MX_(n-1)X′]⁻+XY-   [RMIM]⁺[ML_(n)]⁻+L′→[RMIM]⁺[ML_(n-1)(L′)]⁻+L    Metallic Oxidative Addition Reactions:-   [A]⁻[MIM]⁺—G—ML_(n)+XY→[A]⁻[MIM]⁺—G—ML_(n)(X)(Y)-   [RMIM]⁺[ML_(n)]⁻+XY→[RMIM]⁺[ML_(n)(X)(Y)]⁻-   [RMIM]⁺[ML_(n)]⁻+XY→[RMIM]⁺[ML_(n-1)(X)(Y)]⁻+L

In the above reactions, and throughout the specification, the variablesare described as follows: “A” designates an anion of an ionic liquid;“Y” designates a cation; “BMIM” denotes 1-butyl-3-methylimidazolium;“MIM” denotes a substituted methylimidazolium with a group designated“G” denoting a hydrocarbyl group linking an imidazolium ring with afunctional group such as, for example, NH₂, NR₂, SO₃H, CN, and OCH₃; “X”designates an anion in a compound which is not an ionic liquid which mayinclude, but is not limited to, a halide atom; “Z” denotes a base; “L”and “L′” designate a dative covalent ligand; “M” denotes a metal atom;“R” is an alkyl group; and n is a number ranging from 1 to 8. The term“alkyl” as used herein includes linear, branched, or cyclic alkylgroups, containing from 1 to 24 carbon atoms, or from 1 to 12 carbonatoms, or from 1 to 5 carbon atoms. This term applies also to alkylmoieties contained in other groups such as haloalkyl, alkaryl, oraralkyl. The term “alkyl” further applies to alkyl moieties that aresubstituted, for example, with carbonyl functionality. In the abovechemical formulas and in all chemical formulas throughout this document,it is understood that the variables such as R and X are not onlyindependently selected relative to other R and X groups bearingdifferent superscripts, but are also independently selected relative toany additional species of the same R or X group.

For most of the applications envisioned for the mixtures disclosedherein, the chemical reaction between the ionic liquid and at least aportion of the gas to provide the mixture should have a Gibb's freeenergy (ΔG_(rxn)) of less than +1.3 kcal/mol (K_(eq)˜0.1), whichcorresponds to at least 10% utilization of ionic liquid reactive sitesat 25° C. and 760 Torr. In certain embodiments, the ΔG_(rxn) for thechemical reaction between the ionic liquid and at least a portion of thegas is equal to or less than about −0.5 kcal/mol for a temperatureencompassing the liquidous range of the ionic liquid.

In certain preferred embodiments, the operable temperature range for thechemical reaction between the ionic liquid and at least a portion of thegas contained therein may range from the melting point of the one ormore gases disposed therein to the decomposition temperature of theionic liquid, or from about −100° C. to about 120° C., or from about 0°C. to about 50° C. The chemical reaction can occur with an amount of thegas ranging from at least a portion of the gas contained therein tosubstantially all of the gas contained therein. However, in embodimentswherein at least a portion of the gas is dissolved in anothernon-reactive liquid, the operable temperature may be less than themelting point of the gas(es) contained therein. The ionic liquid may bein a liquid phase prior to, during, and/or after the chemical reactionwith at least a portion of the gas to provide the mixture. In oneparticular embodiment, the reaction may take place at room temperaturewherein the ionic liquid is in the liquid phase and the reaction occursupon introduction of the gas. In these embodiments, the gas may becompressed or at sub-ambient pressures. In another embodiment, the ionicliquid can be cooled to slow the rate of reaction, to control the rateof heat evolution, and/or to accommodate the transfer of at least aportion of the gas. In yet another embodiment, heat can be added to meltthe ionic liquid, to increase the rate of reaction, and/or toaccommodate transfer of one or more gases. In still a furtherembodiment, one or more gases can be supplied in a liquid phase solutionwhich is then contacted with the ionic liquid. In yet other embodiments,the chemical reaction occurs when the ionic liquid is in the solidstate, or as a liquid deposited upon at least a portion of a reactive ornon-reactive solid support such as a porous member, or as an ionicliquid dissolved in another reactive or non-reactive fluid. In all ofthese embodiments, the resulting mixture may be a liquid, a crystallinesolid, a glassy solid, or a mixture thereof.

As mentioned previously, the mixture, which is the product of thechemical reaction of an ionic liquid and at least a portion of the gasdisposed therein, may be used to store and dispense one or more gases toa point of use. The term “gas” as used herein relates to one or morecompounds having a vapor pressure of greater than 760 Torr at atemperature of about 35° C. The term “gas” also encompasses one or moregases that are delivered directly to the chemical reaction with theionic liquid or “neat” or, alternatively, delivered as a vaporizedliquid, a sublimed solid and/or transported by a non-reactive liquid orgas such as, for example, an additive gas or an inert gas, into directcontact with the ionic liquid.

The portion of the gas that is chemically reacted with the ionic liquidcan be viewed in terms of capacity. The term “total capacity”, asreferred to herein, is defined as the number of moles of at least aportion of the gas that will react with one liter of the ionic liquid ata given temperature and pressure to provide the mixture. The term“working capacity (C_(w))”, as referred to herein, is defined as thenumber of moles of gas that is chemically reacted per liter of ionicliquid which is initially stored and is subsequently removable from theliquid during the dispensing operation. In certain embodiments, thetemperature and pressure range for the dispensing operation, i.e., theseparation of the gas from the mixture, may be a temperature rangingfrom 0 to 50° C. and a pressure ranging from 20 to 760 Torr. Workingcapacity can be determined by using the following equation (1):C _(w)=([moles of chemically reacted gas within the mixture]−[moles ofchemically reacted gas remaining in mixture after delivery])/(liters ofionic liquid)  (Equation 1)

The chemical reaction between the at least a portion of the gas and theionic liquid is reversible and the term “percent reversibility”describes the percentage of the gas that is initially reacted with theionic liquid and subsequently removable from the mixture by a variety ofmeans for a given pressure range. Percent reversibility can bedetermined by using the following equation (2):% Reversibility=([moles of chemically reacted gas within themixture]−[moles of chemically reacted gas remaining in mixture afterdelivery])/(moles of initially reacted gas)]*100  (Equation 2)In certain embodiments, the pressure range is from 20 to 760 Torr andthe percent reversibility is at least 15% or greater, at least 35% orgreater, or at least 65% or greater.

One of the difficulties in the development of a suitable storage anddelivery system is the matching of a suitable ionic liquid with one ormore gases through prediction of the ΔG_(rxn). To minimizeexperimentation and project the viability of possible systems, quantummechanical methods can be used to predict molecular structures. DensityFunctional Theory (DFT) is a popular ab initio method that can be usedto determine a theoretical value for the change in electronic energy fora given reaction (ΔE_(rxn)=sum of E_(products)−sum of E_(reactants))between the ionic liquid and at least a portion of the gas. Thefollowing is a discussion for this determination. The calculations areassumed to have an error of approximately ±3 kcal/mol.

In one particular embodiment, the mixture comprises the gas phosphine(PH₃). The reaction of one molar equivalent of PH₃ gas with one molarequivalent of an ionic liquid [IL] in the liquid phase to provide amixture is represented by the equation 3:IL+PH₃(g)← →IL—PH₃  (Equation 3)K_(eq)=[IL—PH₃]/[IL] [PH₃]  (Equation 4)The equilibrium constant for this reaction, K_(eq), is described byequation 4, where the concentration of PH₃, [PH₃], is in units ofatmospheres. K_(eq) is dependent upon the change in Gibbs free energyfor the reaction, ΔG_(rxn), which is a measure of the binding affinitybetween PH₃ and A. The relationships between ΔG, K, and temperature (inKelvin) are given in equations 5 and 6.ΔG=ΔH−TΔS  (Equation 5)ΔG=—RTInK  (Equation 6)The value ΔE_(rxn), can be used as an approximate value for the changein enthalpy (ΔH, see equation 5). Also, if it is assumed that thereaction entropy (ΔS) is about the same for similar reactions, e.g.,reversible reactions under the same temperature and pressure conditions,the values calculated for ΔE_(rxn) can be used to compare againstΔG_(rxn) for those reactions on a relative basis, i.e., ΔG_(rxn) isapproximately proportional to ΔE_(rxn). Thus, the values calculated forΔE_(rxn) can be used to help predict ionic liquids having theappropriate reactivity for a given gas. In the above illustration, itassumed that substantially all of the phosphine gas reacts with theionic liquid.

It has been found that certain mixtures—wherein the ionic liquid and theone gas comprise a Lewis acid/base system or a Lewis base/acidsystem—can be established from the Gibbs free energy of reaction(ΔG_(rxn)) for a given system. In a mixture having an ionic liquid and agas with opposing Lewis acidity or basicity, the ΔG_(rxn) for storingand delivering the gas, and for the operable temperature and pressure,may range from about +1.3 to about −4.5 kcal/mole. There also exists anoptimum ΔG_(rxn) for a given temperature and pressure range, whichcorresponds to a maximum working capacity for the liquid. In referenceto the gas PH₃, if the magnitude of ΔG_(rxn) (and thus, K_(eq)) is toosmall, the ionic liquid will have insufficient capacity for PH₃. Thisinsufficient capacity may be compensated for by selecting an ionicliquid with a higher concentration of PH₃ reactive groups. If themagnitude of ΔG_(rxn) (and thus, K_(eq)) is too large, an insufficientamount of PH₃ will be removable at the desired delivery temperature. Forthe reaction of PH₃ with an ionic liquid, IL, at 25° C. and in thepressure range 20 to 760 Torr, the optimum value range for ΔG_(rxn) isabout from −0.5 to −1.6 kcal/mol. In certain mixtures for gas storageand delivery that involve the reaction of a single equivalent of gaswith an ionic liquid having a single equivalent of Lewis acid/basegroup, the optimum ΔG_(rxn) will be about −1.1 kcal/mol at 25° C. andbetween 20 to 760 Torr. The situation, however, may be more complex forother mixtures, e.g., if the gas and ionic liquid react to provide amixture that is a solid complex or if more than one molar equivalent ofgas reacts with an ionic liquid having more than one molar equivalent ofa Lewis acid/base group.

The term “ionic liquid” as used herein describes molten salts that arecomposed of anions and cations and which, as mentioned previously, havea molten phase below about 120° C. In certain embodiments, the ionicliquid may be represented by the empirical formula A_(x)Q_(y), where Ais a monoanion or polyanion, Q is a monocation or polycation, x is anumber ranging from 1 to about 4, and y is a number ranging from 1 toabout 4. The reactivity of the ionic liquid with the at least a portionof the gas may be determined by the character of the cation, the anion,or by the combination of the cation and anion. A wide variety of anionscan be matched with the cation component of the ionic liquids. Oneexample of an anion is a metal halide derivative, i.e., metal fluoride,metal bromide, metal chloride, and metal iodide. Exemplary metals forsupplying the anion component may include copper, aluminum, iron, zinc,tin, antimony, titanium, niobium, tantalum, gallium, and indium. Inembodiments wherein the metal halide anion is derived form a metalchloride, examples of metal chloride anions include, but are not limitedto, CuCl₂ ⁻, Cu₂Cl₃ ⁻, AlCl₄ ⁻, Al₂Cl₇ ⁻, ZnCl₃ ⁻, ZnCl₄ ²⁻, Zn₂Cl₅ ⁻,FeCl₃ ⁻, FeCl₄ ⁻, Fe₂Cl₇ ⁻, CrCl₄ ⁻, TiCl₅, TiCl₆ ²⁻, SnCl₅ ⁻, SnCl₆ ²⁻,and InCl₄ ⁻. Other classes of anions include carboxylates, fluorinatedcarboxylates, sulfonates, fluorinated sulfonates, sulfates, imides,borates, phosphates, antimonates, etc. Some examples of these anionsinclude, but are not limited to, BF₄ ⁻, PF₆ ⁻, SbF₆ ⁻, p-CH₃—C₆H₄SO₃ ⁻,CF₃SO₃ ⁻, CH₃SO₄ ⁻, CH₃CH₂SO₄ ⁻, NO₃ ⁻, (CF₃SO₂)₂N⁻, (NC)₂N⁻,(CF₃SO₂)₃C⁻, CH₃COO⁻ and CF₃COO⁻.

In certain embodiments, the ionic liquid may act as a Lewis acid orLewis base (including a Brønsted acid or base), although other types ofreactions may occur. In these embodiments and others, exemplary ionicliquids comprise salts of tetraalkylphosphonium, tetraalkylammonium,N-alkylpyridinium or 1,3-dialkylimidazolium cations. Common cations inthe ionic liquid contain C₁₋₂₀ alkyl groups, including but not limitedto, the ethyl, butyl and hexyl derivatives of1-alkyl-3-methylimidazolium and N-alkylpyridinium. Still other cationsinclude pyrrolidinium, pyridazinium, pyrimidinium, pyrazinium,pyrazolium, triazolium, thiazolium, oxazolium, guanidinium, andisouroniums.

In embodiments wherein the gas disposed within the mixture is phosphineor arsine and the ionic liquid is a Lewis acid, the anion component ofthe ionic liquid may be a chlorocuprate or chloroaluminate and thecation component may be derived from a 1,3-dialkylimidazolium salt.

In embodiments wherein the gas is a Lewis acidic gas, the anion, cation,or both anion and cation of the corresponding ionic liquid within themixture can be Lewis basic. Examples of Lewis basic anions that comprisethe Lewis basic ionic liquid include carboxylates, fluorinatedcarboxylates, sulfonates, fluorinated sulfonates, imides, borates,chloride, etc. Common anion forms include BF₄ ⁻, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻,CH₃COO⁻, CF₃COO⁻, CF₃SO₃ ⁻, p-CH₃—C₆H₄SO₃ ⁻, (CF₃SO₂)₂N⁻, (NC)₂N⁻,(CF₃SO₂)₃C⁻, chloride, and F(HF)_(n) ⁻. Other anions includeorganometallic compounds such as alkylaluminates, alkyl- or arylborates,as well as transition metal species. Preferred anions include BF₄ ⁻,p-CH₃—C₆H₄SO₃ ⁻, CF₃SO₃ ⁻, (CF₃SO₂)₂N⁻, (NC)₂N⁻(CF₃SO₂)₃C⁻, CH₃COO⁻ andCF₃COO⁻. Ionic liquids comprising cations that contain Lewis basicgroups may also be used in reference to storing gases having Lewisacidity. Examples of Lewis basic cations include those comprising ringswith multiple heteroatoms.

In certain embodiments, the ionic liquid may be classified as“task-specific” or bear reactive functional groups on the cation and/oranion. Such ionic liquids can be prepared, for example, usingfunctionalized cations and/or anions containing a Lewis base or Lewisacid functional group. Examples of task specific ionic liquids includeaminoalkyl, such as aminopropyl; cyanoalkyl, such as cyanoethyl andcyanopropyl; ureidopropyl, and thioureido derivatives of the abovecations. Specific examples of task-specific ionic liquids containingfunctionalized cations include salts of 1-alkyl-3-(3-aminopropyl)imidazolium, 1-methoxyethyl-3-methylimidazolium,1-alkyl-3-(3-cyanopropyl)imidazolium,1-alkyl-3-(3-ureidopropyl)imidazolium,1-alkyl-3-(3-thioureidopropyl)imidazolium,1-methyl-3-(3-oxobutyl)imidazolium,1-alkyl-4-(2-diphenylphosphanylethyl)pyridinium,1-alkyl-3-(3-sulfopropyl)imidazolium, andtrialkyl-(3-sulfopropyl)phosphonium, andtrialkyl(tetrahydrofuran-2-ylmethyl)phosphonium. Specific examples oftask specific ionic liquids containing functionalized anions includesalts of 2-(2-methoxyethoxy)ethyl sulfate, 2-aminoethanesulfonate and2-acetylaminoethanesulfonate.

In still other embodiments, the ionic liquid may comprise a cationand/or anion that bear a chiral center. Such ionic liquids can beprepared, for example, using reaction precursors that contain at leastone chiral center. Specific examples of ionic liquids containing chiralcations include salts of(S)-4-isopropyl-2-ethyl-3-methyl-4,5-dihydrooxazol-3-ium,(R)-4-isopropyl-2-ethyl-3-methyl-4,5-dihydrooxazol-3-ium,(S)-(1-hydroxymethylpropyl)trimethylammonium, and(R)-(1-hydroxymethylpropyl)trimethylammonium,(S)-4-ethyl-2-isopropyl-3-methyl-4,5-dihydrothiazol-3-ium, and(R)-4-ethyl-2-isopropyl-3-methyl-4,5-dihydrothiazol-3-ium. Specificexamples of ionic liquids containing chiral anions include salts of(S)-lactate, (R)-lactate, (S)-camphorsulfonate, (R)-camphorsulfonate,(S)-butane-2-sulfonate, and (R)-butane-2-sulfonate. The chiral cationand/or anion may also bear a reactive functional group. In the aboveexamples, (R) and (S) denote stereochemistry orientation.

As is known in the synthesis of halometallate ionic liquids, the type ofmetal halide and the amount of the metal halide employed has an effecton the Lewis acidity of the ionic liquid. For example, when aluminumtrichloride is added to a chloride precursor, the resulting anion may bein the form AlCl₄ ⁻ or Al₂Cl₇ ⁻. The two anions derived from aluminumtrichloride have different acidity characteristics, and these differingacidity characteristics impact on the type of gases that can bereactively stored.

In certain embodiments, the Lewis acidic or Lewis basic ionic liquidsare prepared from one or more halide compounds. Examples of halidecompounds from which Lewis acidic or Lewis basic ionic liquids can beprepared include: 1-ethyl-3-methylimidazolium bromide;1-ethyl-3-methylimidazolium chloride; 1-butyl-3-methylimidazoliumbromide; 1-butyl-3-methylimidazolium chloride;1-hexyl-3-methylimidazolium bromide; 1-hexyl-3-methylimidazoliumchloride; 1-methyl-3-octylimidazolium bromide;1-methyl-3-octylimidazolium chloride; monomethylamine hydrochloride;trimethylamine hydrochloride; tetraethylammonium chloride; tetramethylguanidine hydrochloride; N-methylpyridinium chloride;N-butyl-4-methylpyridinium bromide; N-butyl-4-methylpyridinium chloride;tetrabutylphosphonium chloride; and tetrabutylphosphonium bromide.

It is believed that through the proper choice of the anion componentand/or the cation component, an ionic liquid can be selected for optimumreactivity with at least a portion of the gas. The following tables Iand II provide non-limiting examples of mixtures described herein thatinclude an ionic liquid and a gas which may be a Lewis acidic or a Lewisbasic gas. TABLE I Exemplary Mixtures of Ionic Liquid and Gas whereinthe gas is a Lewis Basic Gas Anion Cation Gas (Lewis Basic ComponentsComponents Gas) Cu₂Cl₃ ⁻ 1-Butyl-3-methylimidazolium PH₃ CuCl₂ ⁻1-Hexyl-3-methylimidazolium AsH₃ Al₂Cl₇ ⁻1-Butyl-2,3-dimethylimidazolium SbH₃ FeCl₄ ⁻ N-Hexylpyridinium NH₃ FeCl₃⁻ 1-butyl-1-methylpyrrolidinium H₂NCH₃ ZnCl₃ ⁻Trihexyl(tetradecyl)phosphonium P(CH₃)₃ CrCl₄ ⁻ Methyl(trioctyl)ammoniumH₂Se Hexamethylguanidinium (CH₃)₂O 1-methyl-3-(3- COCl₂sulfopropyl)imidazolium trioctyl-(3-sulfopropyl)phosphonium CH₂(O)CH₂

TABLE II Exemplary Mixtures of Ionic Liquid and Gas wherein the gas is aLewis Acidic Gas Gas (Lewis Anion Components Cation Components AcidicGas) BF₄ ⁻ 1-Butyl-3-methylimidazolium BF₃ CF₃SO₃ ⁻1-Hexyl-3-methylimidazolium B₂H₆ FSO₃ ⁻ 1-Butyl-2,3-dimethylimidazoliumSiF₄ Cl⁻ N-Hexylpyridinium PF₅ ClO₄ ⁻ 1-butyl-1-methylpyrrolidinium AsF₅CH₃CO₂ ⁻ Trihexyl(tetradecyl)phosphonium GeH₄ (CF₃SO₂)₂N⁻Methyl(trioctyl)ammonium GeF₄ B(CN)₄ ⁻ Hexamethylguanidinium Ga₂H₆CH₃SO₄ ⁻ 1-alkyl-3-(3- SnH₄ cyanopropyl)imidazolium 2-(2-ethoxyethoxy)-1-methoxyethyl-3- SF₄ ethylsulfate methylimidazolium (S)-lactate(S)-4-isopropyl-2-ethyl-3-methyl- WF₆ 4,5-dihydrooxazol-3-ium

The following are non-limiting examples of gases wherein at least aportion of the gas may react with the ionic liquid to provide themixture described herein or a component thereof:

-   boron-containing gas (e.g., B₂H₆, BH₃, BH₂R, BHR₂, B(CH₃)₃, BR₃,    BF₃, BCl₃, BX₃, BXR₂, BX₂R,);-   aluminum-containing gas (e.g., Al₂H₆, AlH₃, AlH₂R, AlHR₂, AlR₃);-   phosphorous-containing gas (e.g., PH₃, PH₂R, PHR₂, P(CH₃)₃, PR₃,    PF₃, PX₃, PF₅, PX₅, PXR₂, PX₂R,);-   arsenic-containing gas (e.g., AsH₃, AsH₂R, AsHR₂, AsR₃, AsF₅, AsX₅,    AsX₃, AsXR₂, AsX₂R,);-   ether-containing gas (e.g., O(CH₃)₂, O(CH₂CH₃)₂, CH₂(O)CH₂ (ethylene    oxide)), CH₂(O)CHCH₃ (propylene oxide), OR₂);-   nitrogen-containing gas (e.g., N₂, NO, NO₂, N₂O, NOCl, NOX, NH₃,    N(CH₃)₃, NR₃, NR₂H, NRH₂, HCN, ClCN, C₂N₂);-   antimony-containing gas (e.g., SbH₃, SbH₂R, SbHR₂, SbR₃);-   bismuth-containing gas (e.g., BiH₃, BiH₂R, BiHR₂, BiR₃);-   selenium-containing gas (e.g., SeH₂, SeHR, SeR₂ SeX₂, SeF₆, SeX₆);-   gallium-containing gas (e.g., Ga₂H₆, GaH₃, GaH₂R, GaHR₂, GaR₃);-   silicon-containing gas (e.g., SiH₄, Si(CH₃)₄, SiH₃R, SiH₂R₂, SiH₃R,    SiR₄, SiF₄, SiCl₄, SiX₄, SiHX₃, SiH₂X₂, SiH₃X, SiXR₃, SiX₂R₂, SiX₃R,    SiH₃(OR), SiH₂(OR)₂, SiH(OR)₃, Si(OR)₄, SiR₃(OR), SiR₂(OR)₂,    SiR(OR)₃, SiX(OR)₃, SiX₂(OR)₂, SiX₃(OR));-   germanium-containing gas (e.g., GeH₄, Ge₂H₆, GeH₃R, GeH₂R₂, GeHR₃,    GeR₄, GeF₄, GeX₄);-   tin-containing gas (e.g., SnH₄, SnH₃R, SnH₂R₂, SnHR₃, SnR₄, SnH₃X,    SnH₂X₂, SnHX₃, XSnR₃, X₂SnR₂, X₃SnR);-   tellurium-containing gas (e.g., TeH₂, TeHR, TeR₂, TeF₆);-   halide gases (e.g., F₂, Cl₂, Br₂, 12, SF₄)-   halocarbonyl-containing gas (e.g., COCl₂, COF₂, COX₂, COF₃, CO(CF₃)₂    (hexafluoroacetone)); and-   oxygen-containing gas (e.g., O₂, SO₂F₂, SO₂Cl₂, SO₂X₂ provided that    if the mixture contains only one chemically reacted gas then the    chemically reacted gas is not CO₂ or COS).

In the above formulas, the variable R is independently a straight,branched or cyclic alkyl group and the variable X is independently ananion which may include, but is not limited to, a halide atom. In theabove chemical formulas and in all chemical formulas throughout thisdocument, it is understood that the variables such as R and X are notonly independently selected relative to other R and X groups bearingdifferent superscripts, but are also independently selected relative toany additional species of the same R or X group. For example, in theformula BXR₂ the two R groups need not be identical to each other and,in the formula SeX₆ the 6 X atoms need not be identical to each other.

At least a portion of the chemically reacted gas, optionally theunreacted gas, or both may be separated from the mixture using a varietyof methods and systems. The choice of separation method may varydepending upon the strength of the bond between the chemically reactedportion of the gas and the ionic liquid, the solubility of unreactedportion of the gas if contained within the mixture, or both. Mixturesbased on relatively weak bonds, e.g. ΔG>−4.5 kcal/mol, are well suitedfor sub-atmospheric delivery systems. In these embodiments, the bondbetween the ionic liquid and at least a portion of the chemicallyreacted gas can be readily broken thereby allowing the gas or gases tobe removable under the conditions of a given process. The gas can beremoved, for example, via reduced pressure, addition of heat, or acombination of both. Examples of additional separation methods that maybe used alone or in combination to separate at least a portion of thechemically reacted and/or unreacted gases from the mixture includescrubbing, distillation, evaporation, membrane separation, includingpervaporation, and extraction.

In certain embodiments, the mixture described herein may be storedwithin an enclosed storage vessel such as, but not limited to, a gascylinder with a pressure regulator. At least a portion of the chemicallyreacted gas, the unreacted gas, or both may be separated from themixture using a low pressure gas delivery system. In these embodiments,the chemically reacted gas and optionally the unreacted gas may beremoved from the mixture by creating a pressure differential. In this orin other embodiments, other known methods for enhancing the removal ofat least a portion of chemically reacted and/or unreacted gas can beused such as agitation and liquid aerosolization. One particular exampleof enhancing the removal of at least a portion of the chemically reactedand/or unreacted gas from the mixture is by introducing an inertgas—such as any of the inert gases defined herein—below the surface ofthe mixture (e.g., the liquid gas interface) contained within thevessel. The introduction of an inert gas may, for example, promote gasbubble formation which can comprise the desired gas to be deliveredallowing the desired gas to be removed from the vessel or reside withinthe headspace. The foregoing example, which may be used by itself or inconjunction with the establishment of a pressure differential, can makethe removal of the desired gas from the mixture from the vessel and/orthe head space of the vessel more efficient. In yet another embodiment,the inert gas used to enhance removal of the desired gas can also serveas a carrier to transport the desired gas to a process or point of use.In this embodiment, the inert gas when acting as a carrier gas can beintroduced below the liquid/gas interface, directly into the headspaceof the vessel containing the gas/ionic liquid mixture, or both.

In yet another embodiment, at least a portion or all of the unreactedgas may be separated from the mixture while retaining the chemicallyreacted gas within the mixture using a freeze-pump-thaw method. In thisregard, the temperature of the mixture containing the chemically reactedgas, ionic liquid, and unreacted gas, is reduced to solidify the ionicliquid mixture such that the physical solubility of the unreacted gaswould fall to substantially zero while the chemically reacted gas wouldremain within the mixture. The unreacted gas can then be readily removedfrom the mixture while the ionic liquid having the chemically reactedgas disposed therein remains solid. Next, the temperature of the mixturemay be increased to liquefy the ionic liquid mixture thereby leaving themixture containing the chemically reacted gas which is substantiallyfree (i.e., less than 5%, or less than 1%, or less than 0.1% by volume)of unreacted gas.

The mixture described herein is advantageous for separation andextraction applications. Liquid and solid mixtures can be used toseparate at least a portion of a chemically reacted gas from theunreacted portion of the gas which could be an additive gas, an inertgas, and/or the unreacted portion of the gas by passing the one or moregases through the reactive ionic liquid or a solution containing thereactive ionic liquid. If the gas-ionic liquid bond of a mixture issufficiently weak, the reaction may be reversed, e.g. by applying avacuum and/or heat, allowing the original ionic liquid to be reusedand/or allowing the reacted portion of gas to be recovered. The gas canbe separated from unreactive or less reactive gases by various means. Inother embodiments, a mixture in the liquid phase can be decanted orotherwise removed from another liquid phase (e.g., other unreactedliquids) if the components of the liquid are immiscible with the liquidmixture or a solution containing the mixture. In still anotherembodiment, the reacted portion of the gas, the unreacted portion of thegas, and/or the ionic liquid can be separated from a solidifiedcomponent via filtration.

The mixture described herein may comprise additional components whichmay include, but are not limited to, water, organic solvents, otherionic liquids, and solid supports.

In certain embodiments, some mixtures may be advantageously used as areaction medium for chemical reactions. In these embodiments, themixture may be used to provide, for example, a reagent for the chemicalreaction which may be the ionic liquid, the chemically reacted portionof the gas, the unreacted portion of the gas, and/or the mixture itself.Some of these may be useful as reaction media for chemical reactionssuch as Friedel-Craft acylation, polymerization or oligomerization,hydroformylation, hydrogenation, olefin methathesis, and various otherorganic transformations, especially those requiring a polar aproticsolvent. Some of the mixtures may be useful as recyclable reaction mediain which the at least a portion of the gas component of the mixture(reacted and/or unreacted) serves as a catalyst or stoichiometricreactant. In these embodiments, the mixture can be regenerated bypurifying the remaining ionic liquid and adding an additional amount ofgas.

Certain mixtures may be advantageously used as heat transfer fluids. Forexample, the separation or evolution of gas from the mixture may resultin a temperature drop that can be used, for example, to cool a system.

In certain embodiments, the system for storage and dispensing of one ormore chemically-reacted gas, optionally unreacted gas, or both from themixture comprises a storage and dispensing vessel constructed andarranged to hold the mixture, and for selectively flowing such gas intoand out of such vessel. A dispensing assembly is coupled in gas flowcommunication with the storage and dispensing vessel, and constructedand arranged for selective, on-demand dispensing of the gas by thermaland/or pressure differential-mediated evolution from the reactiveliquid-phase medium. The dispensing assembly can be constructed andarranged: (i) to provide, exteriorly of said storage and dispensingvessel, a pressure below said interior pressure, to effect evolution ofthe gas from the mixture, and flow of gas from the vessel through thedispensing assembly; and/or (ii) to provide means for removal of heat ofreaction of at least a portion of the gas with the ionic liquid and forheating the mixture to effect evolution of the gas therefrom, so thatthe gas flows from the vessel into the dispensing assembly.

In certain embodiments, at least a portion of the gas (e.g., chemicallyreacted, optionally unreacted, or both) within the mixture is readilyremovable from the mixture by pressure-mediated and/orthermally-mediated evolution methods. The term “pressure-mediatedevolution” describes establishing certain pressure conditions, whichtypically range from 10⁻¹ to 10⁻⁷ Torr at 25° C., to cause the gas toevolve from the mixture. For example, such pressure conditions mayinvolve the establishment of a pressure differential between the mixturein the vessel, and the exterior environment of the vessel, which causesflow of at least a portion of the gas from the vessel to the exteriorenvironment (e.g., through a manifold, piping, conduit or other flowregion or passage). The pressure conditions effecting gas evolution mayinvolve the imposition on the mixture of vacuum or suction conditionswhich effect extraction of the chemically reacted portion of the gasand/or unreacted gas from the vessel. The term “thermally-mediatedevolution” describes heating the mixture to cause the evolution of atleast a portion of the gas (e.g., chemically reacted gas, optionallyunreacted gas, or both) from the mixture so that the gas can bewithdrawn or discharged from the vessel. Typically, the temperature forthermal-mediated evolution ranges from 30° C. to 150° C.

The mixture may be stored in a vessel that can be gas permeable ornon-permable. In the former embodiments, at least a portion of the gas(e.g., chemically reacted gas, optionally unreacted gas, or both) cangradually evolve from the vessel having the mixture contained therein,over a certain period of time. In the latter embodiments, at least aportion of the gas (e.g., chemically reacted gas, optionally unreactedgas, or both) may evolve from the mixture and occupy any headspacewithin the non-permeable vessel as the mixture achieves chemicalequilibrium.

The mixture and method will be illustrated in more detail with referenceto the following examples, but it should be understood that the mixtureand method described herein is not deemed to be limited thereto.

EXAMPLES General Procedure

The following is a general procedure for establishing the effectivenessof ionic liquids for storing and delivering at least one gas in theexamples. Unless otherwise stated, phosphene (PH₃) and boron trifluoride(BF₃) are used as the exemplary gases for the mixture described herein.

In a glove box, a 25 mL or 50 mL stainless steel reactor or glassSchlenk flask was charged with a known quantity of an ionic liquid orionic liquid solution. The reactor was sealed, brought out of the glovebox, and connected to an apparatus comprising a pressurized cylinder ofpure PH₃ or BF₃, a stainless steel ballast, and a vacuum pump vented toa vessel containing a PH₃ or BF₃ scavenging material. The gas regulatorwas closed and the experimental apparatus was evacuated up to theregulator. Helium pycnometry was used to measure ballast, piping andreactor headspace volumes for subsequent calculations. The apparatus wasagain evacuated and closed off to vacuum. The following steps were usedto introduce PH₃ or BF₃ to the reactor in increments: 1) the reactor wasisolated by closing a valve leading to the ballast, 2) PH₃ or BF₃ wasadded to the ballast (ca. 800 Torr) via a mass flow controller, 3) thereactor valve was opened and the gas pressure was allowed to equilibratewhile the reactor contents were stirred. These steps were repeated untilthe desired equilibrium vapor pressure was obtained. The quantity of PH₃or BF₃ added in each increment was measured by pressure and volumedifference according to the ideal gas law. The amount of reacted PH₃ orBF₃ was determined by subtracting tubing and reactor headspace volumes.

The reacted PH₃ or BF₃ was removed from the mixture by isolating thereactor, evacuating the ballast, and reopening the reactor to allow thegas to evolve from the liquid and expand into the ballast. Thisprocedure was repeated until a desired lower pressure limit wasachieved. The evolved gas was periodically analyzed by mass spectrometryand/or gas chromatography. In all cases the evolved gas wassubstantially unchanged from the starting gas. FIGS. 1 and 2 provideillustrations of the working capacity for some of the followingexemplary mixtures containing PH₃ and BF₃.

Example 1 Mixture Formed from Reaction of Lewis Acidic Ionic LiquidBMIM⁺Al₂Cl₇ ⁻ and PH₃

Molecular modeling was used to calculate a binding energy, ΔE_(rxn), forthis Lewis acidic ionic liquid with PH₃. The ionic liquid was modeled asan ion-pair, using 1,3-dimethylimidazolium as the cation, Al₂Cl₇ ⁻ asthe anion, and it was assumed that one equivalent of PH₃ reacted perequivalent of Al₂Cl₇ ⁻ anion (concentration of Al₂Cl₇ ⁻=3.2 mol/L).Structures were determined based on minimum energy geometry optimizationusing Density Functional Theory (DFT) at the BP level with a doublenumerical (DN**) basis set. This Lewis acidic ionic liquid wascalculated to have a ΔE_(rxn) of 0.71 kcal/mol, which suggests that thereaction is slightly unfavorable, although within the generallimitations of error. To clarify the results of modeling, the followingreaction was run.

In a glove box, 9.07 g of AlCl₃ (2 equivalents) was slowly added to 5.94g (1 equivalent) of 1-butyl-3-methylimidazolium chloride (BMIM⁺Cl)(assuming the anion Al₂Cl₇ ⁻ is formed from reaction stoichiometry of 2equivalents AlCl₃ to 1 equivalent BMIM⁺Cl⁻). A 25 mL reactor was chargedwith 4.61 g of BMIM⁺Al₂Cl₇ ⁻ (density=1.2 g/mL) and the generalprocedure for measuring the reaction with PH₃ was followed. The ionicliquid reacted with 6.9 mmol of PH₃ at room temperature and 776 Torr,corresponding to 1.8 mol PH₃/L of ionic liquid.

The results show % reversibility=89%, working capacity=1.6 mol/L (roomtemperature, 20-760 Torr). The experimental ΔG_(rxn) is approximately 0kcal/mol at 25° C. These results show that the ionic liquid BMIM⁺Al₂Cl₇⁻ is effective as an ionic liquid for PH₃ and suitable for reacting toform a mixture and that the ΔE_(rxn) provides excellent guidance in theselection of a reactive system.

Delivery of the complex formed to storage and delivery system can beeffected by pumping the complex to the vessel.

Example 2 Mixture Formed from Reaction of Lewis Acidic Ionic LiquidBMIM⁺CuCl₂ ⁻ and PH₃

In a glove box, 3.10 g of CuCl was slowly added to a flask charged with5.46 g of BMIM⁺Cl⁻ (1:1 stoichiometry) (assuming the anion CuCl₂ ⁻ isformed from the reaction stoichiometry 1 equivalent CuCl to 1 equivalentBMIM⁺Cl⁻). The mixture was stirred overnight and stored. A glass insertwas charged with 7.71 g of the ionic liquid (density=1.4 g/mL) andplaced into a 50 mL reactor, and the general procedure for measuring PH₃reaction was followed. The Lewis acidic ionic liquid reacted with 7.6mmol of PH₃ at room temperature and 674 Torr, corresponding to 1.4 molPH₃/L of ionic liquid. Equilibrium data points were not obtained and %reversibility and working capacity were not determined.

Example 3 Mixture Formed from Reaction of Lewis Acidic Ionic LiquidBMIM⁺Cu₂Cl₃ ⁻ and PH₃

Molecular modeling was used to approximate the effectiveness ofBMIM⁺Cu₂Cl₃ ⁻ as a reactive liquid. The ionic liquid was modeled as anion-pair, using 1,3-dimethylimidazolium as the cation, Cu₂Cl₃ ⁻ as theanion, and it was assumed that one equivalent of PH₃ reacted with eachequivalent of copper (concentration of Cu reactive groups=9.7 mol/L).Structures were determined based on minimum energy geometry optimizationusing Density Functional Theory (DFT) at the BP level with a doublenumerical (DN**) basis set. This Lewis acidic ionic liquid wascalculated to have an average ΔE_(rxn) of −5.5 kcal/mol for its reactionwith PH₃. The results indicate that this ionic liquid should bind PH₃more strongly than BMIM⁺Al₂Cl₇ ⁻ of Example 1. Since ΔG_(rxn) is smallerin magnitude than ΔE_(rxn) and the optimum ΔG_(rxn) for the pressurerange 20 to 760 Torr at room temperature is ca. −3 kcal/mol, the resultsuggests that the binding properties of BMIM⁺Cu₂Cl₃ ⁻ may be well suitedfor reversibly reacting with PH₃ (i.e., high working capacity and high %reversibility).

In a glove box, 11.6 g of CuCl was slowly added to a round bottom flaskcharged with 10.2 g of BMIM⁺Cl⁻ (2:1 stoichiometry) (assuming the anionCu₂Cl₃ ⁻ is formed from the reaction stoichiometry 2 equivalents CuCl to1 equivalent BMIM⁺Cl⁻). The mixture was stirred overnight. Aglass-insert was charged with 12.02 g of the ionic liquid (density=1.8g/mL) and placed into a 50 mL reactor, and the general procedure formeasuring PH₃ reaction was followed. The ionic liquid reacted with 51mmol of PH₃ at room temperature and 736 Torr, corresponding to 7.6 molPH₃/L of ionic liquid.

The results show % reversibility=84%, working capacity=6.4 mol/L (roomtemperature, 20-736 Torr). The experimental ΔG_(rxn) is approximately−0.7 kcal/mol at 22° C.

Example 4 Mixture Formed from Reaction of Lewis Acidic Ionic LiquidEMIM⁺Cu₂Cl₃ ⁻ and PH₃

In a glove box, 11.49 g of CuCl was slowly added to a glass vial chargedwith 8.51 g of 1-ethyl-3-methylimidazolium chloride (EMIM⁺Cl⁻) (2:1stoichiometry). (It is assumed the anion Cu₂Cl₃ ⁻ is formed from thereaction stoichiometry 2 equivalents CuCl to 1 equivalent EMIM⁺Cl⁻). Themixture was stirred overnight. A 25 mL reactor was charged with 8.49 gof the ionic liquid (density=1.8 g/mL), and the general procedure formeasuring PH₃ reaction was followed. The ionic liquid reacted with 35mmol of PH₃ at room temperature and 729 Torr, corresponding to 7.4 molPH₃/L of ionic liquid. Equilibrium data points were not obtained and %reversibility and working capacity were not determined.

Example 5 BMIM⁺BF₄ ⁻, Lewis Base Ionic Liquid For PH₃

A 50 mL reactor was charged with 3.99 g of BMIM⁺BF₄ ⁻ and the generalprocedure for measuring PH₃ reaction was followed. The ionic liquid isslightly Lewis basic and it does not react with Lewis basic PH₃. TheΔG_(rxn) reaction is ≧0 kcal/mol

Example 6 BMIM⁺AlCl₄ ⁻, Acid/Base Neutral Ionic Liquid For PH₃

A 50 mL reactor was charged with 9.81 g of BMIM⁺AlCl₄ ⁻ formed by addingAlCl₃ to BMIM⁺Cl (1:1 stoichiometry) and the general procedure formeasuring PH₃ reaction was followed. (It is assumed the anion AlCl₄′ isformed from the reaction stoichiometry 1 equivalent AlCl₃ to 1equivalent BMIM⁺Cl⁻). The ionic liquid reacted with 0.44 mmol of PH₃,corresponding to about 0.06 mol PH₃/L of ionic liquid. The AlCl₄ ⁻ anionis not Lewis acidic. It is believed that the small amount of PH₃reaction that was observed was likely due to the presence of a smallconcentration of Lewis acidic Al₂Cl₇ ⁻. This example furtherdemonstrates that a Lewis acidic species is required for reaction withPH₃.

Example 7 Mixture Formed from Reaction of Lewis Basic Ionic LiquidBMIM⁺BF₄ ⁻ and BF₃

Molecular modeling was used to approximate the effectiveness of BMIM⁺BF₄⁻ as a reactive liquid for the chemical complexation of BF₃. UsingSpartan SGI Version 5.1.3, the ionic liquid was modeled as an ion-pair,using 1,3-dimethylimidazolium as the cation, and it was assumed that oneequivalent of BF₃ reacted with the anion from each equivalent ofBMIM⁺BF₄ ⁻ (concentration of BF₄ ⁻ reactive groups=5.4 mol/L).Structures were determined based on minimum energy geometry optimizationusing Density Functional Theory (DFT) at the BP level with a doublenumerical (DN**) basis set. This Lewis basic ionic liquid was calculatedto have a ΔE_(rxn) of −5.5 kcal/mol for its reaction with BF₃.

The modeling results indicate that the binding affinity of this ionicliquid for BF₃ should be similar to the binding affinity betweenBMIM⁺Cu₂Cl₃ ⁻ and PH₃ in Example 3 where ΔE_(rxn) also is calculated tobe −5.5 kcal/mol. Since the reversible reaction between the Lewis acidicBMIM⁺Cu₂Cl₃ ⁻ and Lewis basic PH₃ provides a near optimum workingcapacity, the result suggests that the binding properties of the Lewisbasic BMIM⁺BF₄ ⁻ may be well suited for reversibly reacting with Lewisacidic BF₃ (i.e. high working capacity and high % reversibility).

In a glove box, a 25 mL stainless steel reactor was charged with 8.82 gof BMIM⁺BF₄ ⁻ purchased from Fluka (density=1.2 g/mL), and the generalprocedure for measuring BF₃ reaction was followed. The ionic liquidreacted with 38.4 mmol of BF₃ at room temperature and 724 Torr,corresponding to 5.2 mol BF₃/L of ionic liquid.

The results show % reversibility=70%, working capacity=3.6 mol/L (roomtemperature, 20-724 Torr). The experimental ΔG_(rxn) is −1.6 kcal/mol at22° C. As predicted by molecular modeling, the reaction between BMIM⁺BF₄⁻ and BF₃ behaved similarly to the reaction between BMIM⁺Cu₂Cl₃ ⁻ andPH₃.

Example 8 Mixture Formed from Reaction of Lewis Basic Ionic LiquidBMIM⁺CH₃OCH₂CH₂OCH₂CH₂O₃SO⁻ (BMIM⁺MDEESO4⁻) Containing anEther-Functionalized (Task Specific) Anion and BF₃

In a glove box, a 25 mL Schlenk flask was charged with 1.96 g ofBMIM⁺CH₃OCH₂CH₂OCH₂CH₂O₃SO⁻ from Fluka (density=1.19 g/mL), and thegeneral procedure for measuring BF₃ reaction was followed. The ionicliquid reacted with 21.6 mmol of BF₃ at room temperature and 864 Torr,corresponding to 13.1 mol BF₃/L of ionic liquid. This is consistent withfour equivalents of BF₃ reacting with each equivalent of ionic liquid.

The results show % reversibility=26%, working capacity=3.36 mol/L (roomtemperature, 20-760 Torr). It is assumed that the first equivalent ofBF₃ reacts with the sulfate (ROSO₂O⁻) anion. The sulfate reaction isirreversible at room temperature and gives a new borate anion,BF₃(OSO₂OR)⁻, that forms a new ionic liquid with BMIM⁺.

Example 9 Mixture Formed from Reaction of Lewis Basic Ionic LiquidBMIM⁺OTf⁻ and BF₃

In a glove box, a 25 mL Schlenk flask was charged with 4.11 g ofBMIM⁺OTf⁻ (OTf⁻=CF₃SO₂O⁻) from Acros (density=1.30 g/mL), and thegeneral procedure for measuring BF₃ reaction was followed. The ionicliquid reacted with 17.0 mmol of BF₃ at room temperature and 793 Torr,corresponding to 5.4 mol BF₃/L of ionic liquid. This is consistent withcomplete reaction of one mole of BF₃ per mole of ionic liquid andpartial reaction of a second equivalent of BF₃.

The results show % reversibility=16%, working capacity=0.85 mol/L (roomtemperature, 20-760 Torr). It is assumed that the first equivalent ofBF₃ reacts with the triflate anion. The triflate reaction isirreversible at room temperature and gives a borate anion, BF₃(OSO₂CF₃)⁻that forms a new ionic liquid with BMIM⁺.

Example 10 Mixture Formed from Reaction of Lewis Basic Ionic LiquidBMIM⁺MeSO₄ ⁻ and BF₃

In a glove box, a 25 mL Schlenk flask was charged with 4.16 g ofBMIM⁺MeSO₄ ⁻ (MeSO₄ ⁻=CH₃OSO₂O⁻) from Fluka (density=1.21 g/mL), and thegeneral procedure for measuring BF₃ reaction was followed. The ionicliquid reacted with 33.9 mmol of BF₃ at room temperature and 757 Torr,corresponding to 9.86 mol BF₃/L of ionic liquid. This is consistent withcomplete reaction of one mole of BF₃ per mole of ionic liquid andpartial reaction of a second equivalent of BF₃.

The results show % reversibility=23%, working capacity=2.24 mol/L (roomtemperature, 20-757 Torr). It is assumed that the first equivalent ofBF₃ reacts with the sulfate (MeOSO₂O⁻) anion. The sulfate reaction isirreversible at room temperature and gives a borate anion,BF₃(OSO₂OCH₃)⁻, that forms a new ionic liquid with BMIM⁺.

Example 11 Mixture Formed from Reaction of Lewis Basic Ionic LiquidMMIM⁺MeSo₄ ⁻ Supplied as a Room Temperature Liquid and BF₃

In a glove box, a 25 mL Schlenk flask was charged with 4.07 g ofMMIM⁺MeSO₄ ⁻ (1,3-dimethylimidazolium methylsulfate) supplied as aliquid at room temperature from Fluka (density=1.33 g/mL), and thegeneral procedure for measuring BF₃ reaction was followed. The ionicliquid reacted with 38.9 mmol of BF₃ at room temperature and 817 Torr,corresponding to 12.7 mol BF₃/L of ionic liquid. This is consistent withcomplete reaction of one mole of BF₃ per mole of ionic liquid andpartial reaction of a second equivalent of BF₃.

The results show % reversibility=32%, working capacity=4.03 mol/L (roomtemperature, 20-760 Torr). It is assumed that the first equivalent ofBF₃ reacts with the sulfate (MeOSO₂O⁻) anion. The sulfate reaction isirreversible at room temperature and gives a borate anion, BF₃(OSO₂OCH₃)⁻, that forms a new ionic liquid with MMIM⁺.

Example 12 Mixture formed from reaction of Lewis Basic Ionic LiquidMMIM⁺MeSO₄ ⁻ Supplied as a Room Temperature Solid and BF₃

Pure MMIM⁺MeSO₄ ⁻ ionic liquid is a solid at room temperature, however,the material used in Example 11 was a liquid at room temperature,indicating that the sample was impure. The experiment from Example 11was repeated using a higher purity ionic liquid.

In a glove box, a 25 mL Schlenk flask was charged with 6.39 g ofMMIM⁺MeSO₄ ⁻ (1,3-dimethylimidazolium methylsulfate) supplied as a solidat room temperature from Solvent Innovation (density assumed to be 1.33g/mL, see example 11), and the general procedure for measuring BF₃reaction was followed. The ionic liquid immediately reacted with BF₃ togive a liquid mixture. The ionic liquid reacted with 62.1 mmol of BF₃ atroom temperature and 757 Torr, corresponding to 12.9 mol BF₃/L of ionicliquid. The result indicates that the ionic liquid reacts with BF₃ toabout the same extent whether the ionic liquid is used as an impureliquid or as a solid of higher purity.

Example 13 Mixture Formed from Reaction of Lewis Basic Ionic LiquidEMIM⁺EtSO₄ ⁻ and BF₃

In a glove box, a 25 mL Schlenk flask was charged with 4.18 g ofEMIM⁺EtSO₄ ⁻ (1-ethyl-3-methylimidazolium ethylsulfate) from SolventInnovation (density=1.21 g/mL), and the general procedure for measuringBF₃ reaction was followed. The ionic liquid reacted with 32.5 mmol ofBF₃ at room temperature and 757 Torr, corresponding to 9.42 mol BF₃/L ofionic liquid. This is consistent with complete reaction of one mole ofBF₃ per mole of ionic liquid and partial reaction of a second equivalentof BF₃.

The results show % reversibility=25%, working capacity=2.36 mol/L (roomtemperature, 26-757 Torr). It is assumed that the first equivalent ofBF₃ reacts with the sulfate (EtOSO₂O⁻) anion. The sulfate reaction isirreversible at room temperature and gives a borate anion,BF₃(OSO₂OCH₂CH₃) ⁻, that forms a new ionic liquid with EMIM⁺.

Example 14 Mixture Formed from Reaction of Lewis Basic Ionic Liquid1-(3-cyanopropyl)-3-methylimidazolium tetrafluoroborate ((C₃CN)MIM⁺BF₄⁻) Containing a Nitrile-Functionalized (Task Specific) Cation and BF₃

In a glove box, a 25 mL Schlenk flask was charged with 2.11 g of(C₃CN)MIM⁺BF₄ ⁻ (density=1.87 g/mL), and the general procedure formeasuring BF₃ reaction was followed. The ionic liquid reacted with 9.75mmol of BF₃ at room temperature and 69 Torr, corresponding to 8.64 molBF₃/L of ionic liquid. This is consistent with more than one equivalentof BF₃ reacting with each equivalent of ionic liquid.

It is assumed that BF₃ reacts with the BF₄ ⁻ anion as well as thenitrile group of the functionalized imidazolium cation. In this case,the full theoretical capacity is 15.8 mol/L (7.89 mol of ionicliquid/L). The mixture became too viscous to stir after adding 8.64 mmolof BF₃. The reacted BF₃ was removed under vacuum both at roomtemperature and with external heating, and the viscosity of the liquiddecreased as BF₃ was removed.

Example 15 Mixture Formed from Reaction of Lewis Basic Ionic LiquidBMIM⁺BF₄ ⁻, Lewis Basic Ionic Liquid1-(3-cyanopropyl)-3-methylimidazolium tetrafluoroborate ((C₃CN)MIM⁺BF₄⁻) Containing a Nitrile-Functionalized (Task Specific) Cation, and BF₃

A solution comprising (C₃CN)MIM⁺BF₄ ⁻ and BMIM⁺BF₄ ⁻ was prepared todecrease the viscosity of the mixture resulting from the reaction of BF₃with (C₃CN)MIM⁺BF₄ ⁻. In a glove box, a 25 mL Schlenk flask was chargedwith 1.97 g of (C₃CN)MIM⁺BF₄ ⁻ (density=1.87 g/mL, volume=1.05 mL) and1.33 g of BMIM⁺BF₄ ⁻ (density=1.21 g/mL, volume 1.10 mL). The twoliquids were stirred together to make a solution (estimated density=1.53g/mL) and the general procedure for measuring BF₃ reaction was followed.The ionic liquid solution reacted with 19.7 mmol of BF₃ at roomtemperature and 813 Torr, corresponding to 9.12 mol BF₃/L of ionicliquid solution.

It is assumed that BF₃ reacts with the BF₄ ⁻ anions from both ionicliquids as well as the nitrile group of the functionalized imidazoliumcation. In this case, the full theoretical capacity is 10.45 mol/L (7.72mol/L for (C₃CN)MIM⁺BF₄ ⁻, 2.76 mol/L for BMIM⁺BF₄ ⁻). The mixturebecame slightly cloudy, consistent with a high loading of BF₃, butretained a low enough viscosity to allow stirring. At least a portion ofthe reacted BF₃ was removable under vacuum at room temperature.

Example 16 Mixture Formed from the Contact of Lewis Acidic Ionic Liquid1-butyl-3-methylimidazolium trichloridicuprate (BMIM⁺Cu₂Cl₃ ⁻) with atLeast a Portion of Phosphine (PH₃) Chemically Reacted with the IonicLiquid and Unreacted Gases Nitrogen and Carbon Monoxide; Removal ofNitrogen and Carbon Monoxide from the Resulting Mixture

A 2.2 liter vessel was charged with 1.07 liters of BMIM⁺Cu₂Cl₃ ⁻. Thevessel was placed under vacuum and the ionic liquid was degassed withmixing overnight. Phosphine containing trace levels of nitrogen andcarbon monoxide was introduced into the vessel through a tube below thesurface of the ionic liquid with mixing. The flow of PH₃ was stoppedafter adding about 250 g of PH₃ and the pressure above the ionic liquid(vessel headspace) equilibrated to 690 Torr. At least a portion of thePH₃ was chemically reacted with the BMIM⁺Cu₂Cl₃ ⁻ to provide a mixture.Gas chromatography was used to analyze the approximately 1 liter of gascontained in the vessel headspace. In addition to PH₃, the headspacecontained 89 parts per million (ppm) of nitrogen, 3 ppm of carbonmonoxide, and about 1% by volume hydrogen. The approximately 1 litervolume of gas was removed from the headspace and mixture by exposing thevessel to an evacuated 500 mL ballast a total of 10 times. The headspacewas sampled upon reaching a pressure of 630 Torr and was found tocontain, in addition to PH₃, 4.8 ppm of nitrogen, 0.74 ppm of carbonmonoxide; and less than ½% by volume hydrogen. Upon standing for threedays, the pressure within the vessel equilibrated to 680 Torr and theapproximately 1 liter of gas in the headspace contained 17.7 ppm ofnitrogen, 1.1 ppm of carbon monoxide, and less then ½% by volumehydrogen. Gas was removed from the headspace and mixture by exposing thevessel to an evacuated 500 mL flask (11 times), which reduced the levelsof nitrogen and carbon monoxide to 0.6 ppm and 0.18 ppm, respectively.Most of the remaining gas comprised PH₃ with less than ½% by volume ofhydrogen.

1. A mixture for storage and delivery of a gas comprising: an ionicliquid comprising an anion and a cation; the gas disposed within theionic liquid comprising at least one selected from the group consistingof a boron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a halocarbonyl-containing gas, and anoxygen-containing gas wherein at least a portion of the gas ischemically reacted with the ionic liquid to provide a chemically reactedgas; and optionally an unreacted gas selected from an additive gas, aninert gas, an unreacted portion of the chemically reacted gas, andmixtures thereof.
 2. The mixture of claim 1 wherein the chemicallyreacted gas comprises at least one gas selected from the groupconsisting of phosphine, arsine, stibine, ammonia, hydrogen selenide,hydrogen telluride, phosgene, nitrogen, oxygen, andisotopically-enriched analogs of the at least one gas.
 3. The mixture ofclaim 2 wherein the chemically reacted gas comprises at least one gasselected from phosphine, arsine, and stibine.
 4. The mixture of claim 1comprising the unreacted gas.
 5. The mixture of claim 4 wherein theunreacted gas comprises the additive gas selected from carbon monoxide,carbon dioxide, oxygen, and mixtures thereof.
 6. The mixture of claim 4wherein the unreacted gas comprises the inert gas selected fromnitrogen, helium, neon, hydrogen, methane, argon, krypton, xenon, radon,and mixtures thereof.
 7. The mixture of claim 4 wherein the unreactedgas comprises the unreacted portion of the chemically reacted gas and isat least one gas selected from the group consisting of phosphine,arsine, stibine, ammonia, hydrogen selenide, hydrogen telluride,phosgene, and isotopically-enriched analogs of the at least one gas. 8.The mixture of claim 7 wherein the unreacted portion comprises at leastone gas selected from the group consisting of phosphine, arsine,stibine, and mixtures thereof.
 9. The mixture of claim 1 wherein theionic liquid comprises a Lewis acid and the gas comprises a Lewis base.10. The mixture of claim 9 wherein the cation of the ionic liquidcomprises at least one selected from 1-butyl-3-methylimidazolium,1-ethyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium,1-butyl-2,3-dimethylimidazolium, N-hexylpyridinium,1-butyl-3-methylpyrrolidinium, trihexyl(tetradecyl)phosphonium, andmethyl(trioctyl)ammonium.
 11. The mixture of claim 9 wherein the anionof the ionic liquid is selected from CuCl₂ ⁻, Cu₂Cl₃ ⁻, AlCl₄ ⁻, Al₂Cl₇⁻, ZnCl₃ ⁻, ZnCl₄ ²⁻, Zn₂Cl₅ ⁻, FeCl₃ ⁻, FeCl₄ ⁻, Fe₂Cl₇ ⁻, TiCl₅ ⁻,TiCl₆ ²⁻, SnCl₅, CrCl₄ and SnCl₆ ²⁻.
 12. The mixture of claim 1 whereinthe ionic liquid comprises a Lewis base and the gas comprises a Lewisacid.
 13. The mixture of claim 12 wherein the gas is selected from BF₃,B₂H₆, SiF₄, PF₅, AsF₅, GeH₄, GeF₄, Ga₂H₆, SnH₄, SF₄, and WF₆.
 14. Themixture of claim 12 wherein anion of the ionic liquid comprises at leastone selected from BF₄ ⁻, CF₃SO₃ ⁻, FSO₃ ⁻, Cl⁻, ClO₄ ⁻, CH₃CO₂ ⁻,(CF3SO2)2N⁻, B(CN)₄ ⁻, CH₃SO₄ ⁻, and 2-(2-ethoxy)ethylsulfate, and(S)-lactate.
 15. The mixture of claim 12 wherein the cation of the ionicliquid comprises at least one selected from 1-butyl-3-methylimidazolium,1-ethyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium,1-butyl-2,3-dimethylimidazolium, N-hexylpyridinium,1-butyl-1-methylpyrrolidinium, triheyxyl(tetradecyl)phosphonium,methyl(trioctyl)ammonium, 1-alkyl-3-(3-cyanopropyl)imidazolium,1-methoxyethyl-3-methylimidazolium, and(S)-4-iospropyl-2-ethyl-3-methyl-4,5-dihydrooxazol-3-ium.
 16. Themixture of claim 1 wherein the anion, the cation, or both comprises areactive functional group.
 17. The mixture of claim 1 wherein the anion,the cation, or both comprises a chiral center.
 18. A reaction mediumcomprising the mixture of claim
 1. 19. A mixture for the storage anddelivery of at least one gas: comprising an ionic liquid having Lewisacidity and comprising a dialkyl-imidazolium cation and a chlorocuprateor chloroaluminate anion; at least one gas having Lewis basicity that isdisposed within the ionic liquid and wherein at least a portion of theat least one gas is reversibly chemically reacted with the ionic liquidto provide a chemically reacted gas; and optionally an unreacted gas.20. The mixture of claim 19 wherein the dialkylimidazolium cation is1-butyl-3-methylimidazolium and said anion is selected from the Al₂Cl₇⁻, CuCl₂ ⁻, and Cu₂Cl₃ ⁻.
 21. A mixture for storage and delivery of agas comprising: an ionic liquid having Lewis basicity and comprising ananion selected from BF₄ ⁻, p-CH₃—C₆H₄SO₃ ⁻, CF₃SO₃ ⁻, (CF₃SO₂)₂N⁻,(NC)₂N⁻, (CF₃SO₂)₃C⁻, CH₃COO⁻ and CF₃COO⁻ and a cation selected fromtetraalkylphosphonium, teraalkylammonium, N-alkylpyridinium, and1,3-dialkylimidazolium; the gas wherein at least a portion of the gas isreversibly chemically reacted with the ionic liquid to provide achemically reacted gas wherein the chemically reacted gas has Lewisacidity and is selected from diborane, boron trifluoride, borontrichloride, phosphorous trifluoride, phosphorous tetrafluoride, silicontetrafluoride, germane, germanium tetrafluoride, hydrogen cyanide,isotopically-enriched analogs, and mixtures thereof; and optionally anunreacted gas.
 22. The mixture of claim 21 comprising the unreacted gas.23. The mixture of claim 22 wherein the unreacted gas comprises anadditive gas selected from carbon monoxide, carbon dioxide, oxygen, andmixtures thereof.
 24. The mixture of claim 22 wherein the unreacted gascomprises an inert gas selected from nitrogen, helium, neon, hydrogen,argon, krypton, xenon, radon, and mixtures thereof.
 25. The mixture ofclaim 22 wherein the unreacted gas comprises an unreacted portion of thechemically reacted gas selected from diborane, boron trifluoride, borontrichloride, phosphorous pentafluoride, arsenic pentafluoride, antimonypentafluoride, silicon tetrafluoride, germane, germanium tetrafluoride,hydrogen cyanide, isotopically-enriched analogs, and mixtures thereof.26. The mixture of claim 21 wherein the ionic liquid has a cationcomponent selected from 1-butyl-3-methylimidazolium,1-ethyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium,1-butyl-2,3-dimethylimidazolium, N-hexylpyridinium,1-butyl-1-methylpyrrolidinium, triheyxyl(tetradecyl)phosphonium,methyl(trioctyl)ammonium, 1-alkyl-3-(3-cyanopropyl)imidazolium,1-methoxyethyl-3-methylimidazolium, and(S)-4-iospropyl-2-ethyl-3-methyl-4,5-dihydrooxazol-3-ium, and an anioncomponent selected from BF₄ ⁻, PF₆ ⁻, AsF₆ ⁻, and SbF₆ ⁻.
 27. A methodfor the storage and delivery of a gas selected from the group consistingof a boron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a halocarbonyl-containing gas, anoxygen-containing gas, and mixtures thereof, the method comprising thesteps of: providing an ionic liquid comprising an anion and a cation;reacting at least a portion of the gas with the ionic liquid to providea mixture comprising an ionic liquid and a chemically reacted gas; andseparating the chemically reacted gas from the mixture where the gasafter the separating step has substantially the same chemical identityas the chemically reacted gas prior to the reacting step.
 28. The methodof claim 27 wherein the mixture in the reacting step further comprisesan unreacted gas.
 29. The method of claim 28 wherein the unreacted gascomprises one selected from the group consisting of an additive gas, aninert gas, an unreacted portion of the gas in the reacting step, andmixtures thereof.
 30. The method of claim 27 further comprisingseparating the unreacted gas from the mixture.
 31. The method of claim27 wherein the separating step is conducted using a method selected fromscrubbing, distillation, evaporation, membrane separation, extraction,and combinations thereof.
 32. The method of claim 27 wherein theseparating step is conducted by pressure-mediated evolution,thermally-mediated evolution, or both.
 33. A method for the storage anddelivery of a gas selected from the group consisting of aboron-containing gas, an aluminum-containing gas, aphosphorous-containing gas, an arsenic-containing gas, anether-containing gas, a nitrogen-containing gas, an antimony-containinggas, a bismuth-containing gas, a selenium-containing gas, agallium-containing gas, a silicon-containing gas, a germanium-containinggas, a tin-containing gas, a tellurium-containing gas, ahalogen-containing gas, a halocarbonyl-containing gas, anoxygen-containing gas and mixtures thereof, the method comprising thesteps of: providing an ionic liquid comprising an anion and a cation;reacting at least a portion of the gas with the ionic liquid to providea mixture comprising an ionic liquid and a chemically reacted gas;introducing an unreacted gas comprising an inert gas into the mixture;and separating at least a portion of the chemically reacted gas andoptionally the unreacted gas from the mixture where the chemicallyreacted gas after the separating step has substantially the samechemical identity as the chemically reacted gas prior to the reactingstep.
 34. A method for the removal of at least a portion of an unreactedgas from a mixture comprising a chemically reacted gas, an ionic liquid,and the unreacted gas, the method comprising: providing the ionic liquidcomprising an anion and a cation within a storage vessel; introducingthe unreacted gas to the storage vessel comprising the ionic liquidwherein at least a portion of the unreacted gas resides within aheadspace of the storage vessel; reacting at least a portion of a gasselected from the group consisting of a boron-containing gas, analuminum-containing gas, a phosphorous-containing gas, anarsenic-containing gas, an ether-containing gas, a nitrogen-containinggas, an antimony-containing gas, a bismuth-containing gas, aselenium-containing gas, a gallium-containing gas, a silicon-containinggas, a germanium-containing gas, a tin-containing gas, atellurium-containing gas, a halogen-containing gas, ahalocarbonyl-containing gas, an oxygen-containing gas and mixturesthereof with the ionic liquid to provide the mixture comprising theionic liquid, a chemically reacted gas disposed within the ionic liquid,and the unreacted gas; reducing the temperature of the mixture tosolidify the ionic liquid and provide a solidified mixture comprisingthe ionic liquid and chemically reacted gas wherein the reducingdecreases the solubility of the unreacted gas thereby causing theunreacted gas to evolve into the headspace; removing substantially allof the unreacted gas from the headspace; and increasing the temperatureof solidified mixture to provide a mixture substantially free ofunreacted gas.